Crotch Master from a Rub-Off

Back to main CrotchmasterCrotchmaster to elastic-waist pants

© 2022 Carol Kimball

Copying an Existing Pair of Pants

Pulling a pattern from an existing pair of pants with an elastic band in a self-casing: two pattern pieces. The center front area has the fabric smoothed to the sides; the elastic is stitched through vertically at side fronts and at center back.

If your garment is right-side-out with the raw edges inside, you’ll need to add seam allowances. Here we’ll draw along the raw edges and add dashed stitching lines. The crotch fork on pants is easiest to work with when they’re inside-out.

  1. Turn your pants inside-out (no photo, c’mon, you can figure this out)
  2. Reach up inside, starting at the bottom of one leg, and grab the hem of the other leg.
  3. With your other hand, grab the crotch and pull the second leg inside the first.
  4. Smooth out (as far as possible) so that the front lies flat.

If your garment is right-side-out with the raw edges inside, you’ll need to add seam allowances. Here we’ll draw along the raw edges and add dashed stitching lines. The crotch fork on pants is easiest to work with when they’re inside-out.

Your raw master is often a mess of irregularity, with drawn and pricked lines for seams/necklines of the front AND back, and notes.

The corrected master cleans everything up. If you made a working pattern from it, you’d be re-creating the original garment.

The altered master incorporates corrections: “sleeve length should be 1/2”/1 cm longer” “drop front neckline xx amount” “widen shoulder strap to xx”

The working pattern (yes, we’re up to four) has seam allowances and is what you use to lay out on your fabric.

Keep them in the same envelope (upgrade to a gallon ziplock if necessary). Fold your working pattern pieces with the critical info on the outside. Fold earlier versions into their own sets and pin through all the pieces. When you pull out the pattern and dump the contents, it’s easy to sort out what you want.

With your pants front flat on pattern paper on a pin-able surface (the back layer commonly is visible):

  1. Prick a line of holes down the front fold (or where it would be – this is your grainline).
  2. Draw along the raw edges where you can.
  3. Prick through where the edge lies inside the edge of another section (the front crotch, here).

Lay the pants aside.

  1. Note that the waistband is NOT perpendicular to the grain. If you want your pants to fit and your waistline slants, so must your waistband. We’ll reconcile any difference in angle between the front and back when we do the back.
  2. Extend the upper front edges so that the waistband is the same circumference as the hips.
  3. Add a seam allowance to the hem.
  4. The little red lines are for nips in the seam allowance. They show how far to fold the waistband down, the hems up, and where the side front stitching through the elastic will go.
  5. Label your pattern.

For non-raveling fleece pants, my default is a 3/8” seam allowance. Whether it’s drawn in (the dashed lines) or written doesn’t matter as long as it’s there.

This is close to finished; the back will need to be reconciled with it first. Usually changes will be made to the back, but not always. Don’t cut it out yet.

The angles of the hem allowance must mirror what’s above them, and they may not be the same on each side.

Fold the pattern up on the hem line and trace.

Adding a side seam pocket (this is general theory; it may be reworked/edited at the construction stage).

This pocket is cut in one with the front and back pieces; it’s fastest to sew but takes more fabric, particularly if you’re working with a nap. You can cut the pocket pieces separately and sew them to the side seams at the expense of a little more bulk there.

  1. Place your front pattern on your body.
  2. Position your hand “in your pocket”.
  3. Draw around your hand.
  4. Flip the pocket to the outside.
  5. Add the seam allowance.

If the bottom of the pocket opening is lower than the crease at your hip when you sit down, stuff will fall out of your pocket (maybe not a Kleenex, but a pocket knife, definitely). You can shorten the opening in the pattern or sew up commercial pants: it’s a trade-off between fall-out and being able to get your hand inside.

A slant pocket opening solves this.

Pulling a pattern from the back of pants (or any piece that won’t pin out flat):

  1. Gray pants with a European crotch (the inseam is closer to the front of the body).
  2. Master pattern. The legs have curled/twisted, which is reflected in the width drawn. The back leg is wider than the front.
  3. Front for these pants.
  4. Back with crotch fork as pricked (leg is also pulled under).
  5. Back with crotch unfolded.
  6. Superimposed front and back.